Method for reducing rotational acceleration during an impact to an outside surface of protective headgear

ABSTRACT

A method for reducing rotational acceleration during an impact to an outside surface of protective headgear involves positioning a body between a head of a person and an inside top surface of the protective headgear. The body has a first face and a second face, with the first face providing a slippery exterior surface. Sliding movement along this slippery exterior surface is used to dissipate kinetic energy. In a first embodiment, a head of a person slides along the slippery exterior surface. In a second embodiment, the inside surface of the protective headgear slides along the slippery exterior surface. In a third embodiment, a helmet liner (with the head of a person positioned within it) slides along the slippery exterior surface.

FIELD

There is described a method for reducing rotational acceleration felt by the brain during an impact to an outside surface of protective headgear.

BACKGROUND

U.S. Pat. No. 10,143,255 (Golnaraghi et al) describes a danger of injuries occurring to a head of a person wearing protective head gear as a result of rotational acceleration. The reason for this is that, upon impact, an outer shell of the protective headgear stops instantly, while the head keeps moving. The solution proposed by Golnaraghi et al is to provide an impact diverting mechanism which includes a top layer which attaches to the shell of the helmet and a bottom layer that attaches to the liner of the helmet. The top layer is disposed adjacent to and mechanically connected to the bottom layer. Upon impact, the top layer shifts relative to the bottom layer. This relative movement dissipates kinetic energy.

Golnaraghi et al further describes embodiments that have an intermediate layer positioned between the top layer and the bottom layer. The intermediate layer may include a liquid-gel lubricant to facilitate relative slipping movement of the top layer and the bottom layer. As research in this area continues, there have been various structures proposed that include an intermediate layer to facilitate relative slipping movement of the top layer and the bottom layer. U.S. Patent publication 20130040524 (Halldin et al) titled “Intermediate Layer of Friction Decreasing Material” proposes the use of fibers as friction decreasing material.

SUMMARY

There is provided a method for reducing rotational acceleration during an impact to an outside surface of protective headgear, which involves positioning a body between a head of a person and an inside top surface of a protective headgear. The body has a first face and a second face, with the first face providing a slippery exterior surface. The method involves positioning the second face of the body against one of the head or the inside top surface of the protective headgear, with the slippery exterior surface on the first face engaging the other of the head or the inside top surface of the protective headgear. Upon impact, a sliding movement along the slippery exterior surface takes place of the head or the inside top surface of the protective headgear engaging along the slippery exterior surface.

It will be understood that the method described above is a marked departure from the teachings of the prior art. The body does not have a top layer and a bottom layer that slide relative to each other. There is no intermediate sliding layer to assist relative movement of the top layer and the bottom layer. Instead, the body has a slippery exterior surface and facilitates movement to dissipate kinetic energy using this slippery exterior surface.

There will hereinafter be described a series of alternative embodiments which demonstrate alternative ways of implementing the method using a slippery exterior surface. In a first embodiment, the body is secured to the inside surface of the protective headgear and the head of a person slides along the slippery exterior surface. In a second embodiment, the inside surface of the protective headgear slides along the slippery exterior surface. In a third embodiment, a helmet liner (with the head of a person positioned within it) slides along the slippery exterior surface.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:

FIG. 1 is a partial side elevation view, in section, of a body common to all disclosed embodiments.

FIG. 2 is a schematic diagram illustrating the forces involved in an impact on a protective headgear common to all disclosed embodiments.

FIG. 3 is a partial side elevation view, in section, of a first embodiment using the body of FIG. 1.

FIG. 4 is a partial side elevation view, in section, of a second embodiment using the body of FIG. 1.

FIG. 5 is a partial side elevation view, in section, of a third embodiment using the body of FIG. 1.

DETAILED DESCRIPTION

A method for reducing rotational acceleration during an impact to an outside surface of protective headgear, will now be described with reference to FIG. 1 through FIG. 5.

Structure and Relationship of Parts

Referring to FIG. 2, there is shown the force vectors acting upon protective headgear when an impact occurs. The primary focus of the present invention is the tangential component of the force. Referring to FIG. 1, there is illustrated a body 12. If only the tangential force were being addressed, body 12 could consist only of polymer plastic portion 14 and would not require impact absorbing properties. However, in order to provide body 12 with impact absorbing properties to address the normal component of the impact force it is preferred that body 12 include an open-celled polymer foam portion 16. The open-cell structure provides breathability that can enhance comfort. Body 12 has a first face 18 and a second face 20. First face 18 provides body 12 with a slippery exterior surface. This can be accomplished by using a self-lubricating polymer plastic or, as illustrated here, by applying a coating 22 to a hard polymer plastic layer 14. As will hereinafter be further described, body 12 is secured by mating hook and loop tape fasteners, having a hook tape fastener portion 26 and a loop tape fastener portion 28. A loop tape fastener portion 28 is secured to second face 20.

In describing the method in relation to the various embodiments below, reference will be made to a protective headgear 30, a head 40 of a person and a helmet liner 50.

First Embodiment

Referring to FIG. 3, body 12 is positioned between the head 40 of a person and an inside top surface 32 of the protective headgear 30. Second face 20 of body 12 is secured to inside top surface 32 of protective headgear 30 by mating hook tape fastener portion 26 secured to inside top surface 32 with loop tape fastener portion 28 secured to second face 20.

When assembled as shown and described with the slippery exterior surface on first face 18 engages head 40. Upon impact, a sliding movement takes place with head 40 sliding along the slippery exterior surface on first face 18.

At isolated locations where the hook and loop fasteners are placed, there is little or no motion. However, in areas where there are no hook and loop fasteners and the slippery exterior surface is in direct contact with the head or helmet surface, there is nothing stopping motion from occurring. The slippery exterior surface will allow up to 15 mm of motion, which has proven to be enough to reduce the rotational acceleration of the head by up to 30%.

Although open-cell polymer foam portion 16 is preferred, there are other materials that are known for their impact absorbing properties that could be substituted such as: closed-cell foams, memory-foams or other types of shock-absorbing foams. Although hard polymer plastic layer 14 is preferred for slippery exterior surface, there are other materials that could be substituted and coated to provide the desired slippery surface, such as: conventional thermoplastic, thermoset elastomers, natural or synthetic rubber, plasticized foams, low-density polyethylene or high-density polyethylene. Although hook and loop tape fasteners are preferred, there are other types of mechanical fasteners that could be used buttons or snap fasteners.

Second Embodiment

Referring to FIG. 4, body 12 is again positioned between the head 40 of a person and an inside top surface 32 of protective headgear 30. In this second embodiment, body 12 serves as a helmet liner and second face 20 of body 12 is positioned against, but not necessarily secured to, head 40.

When assembled as shown and described with the slippery exterior surface on first face 18 engages inside top surface 32 of protective headgear 30. Upon impact, a sliding movement takes place with inside top surface 32 sliding along the slippery exterior surface on first face 18. It is to be noted that body 12 is secured to inside top surface 32 of protective headgear 30 by mating hook tape fastener portion 26 secured to inside top surface 32 with loop tape fastener portion 28 secured to first face 18. The idea is to secure body 12 to a portion of inside top surface 32, such as an edge of a rib, that is not directly facing head 40 and allowing sliding to occur on that portion of inside top surface 32 that is directly facing head 40.

Third Embodiment

Referring to FIG. 5, body 12 is again positioned between the head 40 of a person and an inside top surface 32 of protective headgear 30. In this third embodiment, second face 20 of body 12 is secured to inside top surface 32 of protective headgear 30 by mating hook tape fastener portion 26 secured to inside top surface 32 with loop tape fastener portion 28 secured to second face 20. As with the second embodiment, body 12 is secured to inside top surface 32 of protective headgear 30 by mating hook tape fastener portion 26 secured to inside top surface 32 with loop tape fastener portion 28. The idea is to secure body 12 to a portion of inside top surface 32, such as an edge of a rib, that is not directly facing head 40 and allowing sliding to occur on that portion of inside top surface 32 that is directly facing head 40.

When assembled as shown and described with the slippery exterior surface on first face 18 engages head 40 indirectly, by engaging with helmet liner 50 that is secured to head 40. Upon impact, a sliding movement takes place of head 40 (along with helmet liner 50) sliding along the slippery exterior surface on first face 18.

In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements.

The scope of the claims should not be limited by the illustrated embodiments set forth as examples, but should be given the broadest interpretation consistent with a purposive construction of the claims in view of the description as a whole. 

What is claimed is:
 1. A method for reducing rotational acceleration during an impact to an outside surface of protective headgear, comprising: positioning a body between a head of a person and an inside top surface of a protective headgear, the body having a first face and a second face, the first face providing a slippery exterior surface; positioning the second face of the body against one of the head or the inside top surface of the protective headgear, with the slippery exterior surface on the first face engaging the other of the head or the inside top surface of the protective headgear, such that, upon impact, a sliding movement takes place along the slippery exterior surface of the first face.
 2. The method of claim 1, wherein the body has impact absorbing properties.
 3. The method of claim 2, wherein the body is an open-celled polymer foam.
 4. The method of claim 1, wherein the slippery exterior surface is a polymer plastic layer on the first face.
 5. The method of claim 1, wherein the body is held in position within the protective head gear by mechanical fasteners.
 6. The method of claim 5, wherein the mechanical fasteners are hook and loop tape fasteners.
 7. The method of claim 1, wherein the second face of the body is positioned against the inside top surface of the protective headgear and the head slides along the slippery exterior surface on the first face.
 8. The method of claim 1, wherein the second face of the body is positioned against the head and the inside top surface of the protective headgear slides along the slippery exterior surface on the first face.
 9. The method of claim 8, wherein the body is secured to a portion of the inside top surface that does not directly face the head, with sliding occurring on that portion of the inside top surface that is directly facing the head.
 10. The method of claim 8, wherein the body is a helmet liner.
 11. The method of claim 1, wherein the second face of the body is positioned against the inside top surface of the protective headgear and a helmet liner is position on the head and the head, covered by the helmet liner, slides along the slippery exterior surface on the first face.
 12. The method of claim 11, wherein the body is secured to a portion of the inside top surface that does not directly face the head, with sliding to occurring on that portion of the inside top surface that is directly facing the head. 